Client devices such as personal computers (PCs) capable of network connection have become widespread. Along with the widespread use of the devices, the network population of the Internet is increasing. Various services using the Internet have recently been developed for the network users, and there are also provided entertainment services such as games.
One of the services for the network users is a multiuser online network game such as MMORPG (Massively Multiplayer Online Role-Playing Game). In the multiuser online network game, a user connects his/her client device in use to a server that provides the game, thereby doing match-up play or team play with another user who uses another client device connected to the server.
In a general multiuser online network game, each client device sends/receives data necessary for game rendering to/from the server. The client device executes rendering processing using the received data necessary for rendering and presents the generated game screen to a display device connected to the client device, thereby providing the game screen to the user. Information the user has input by operating an input interface is sent to the server and used for calculation processing in the server or transmitted to another client device connected to the server.
However, some network games that cause a client device to execute rendering processing require a user to use a PC having sufficient rendering performance or a dedicated game machine. For this reason, the number of users of a network game (one content) depends on the performance of the client device required by the content. A high-performance device is expensive, as a matter of course, and the number of users who can own the device is limited. That is, it is difficult to increase the number of users of a game that requires high rendering performance, for example, a game that provides beautiful graphics.
In recent years, however, there are also provided games playable by a user without depending on the processing capability such as rendering performance of a client device. In a game as described in International Publication No. 2009/138878, a server acquires the information of an operation caused in a client device and provides, to the client device, a game screen obtained by executing rendering processing using the information.
In the game described above in International Publication No. 2009/138878, the server renders and transfers the game screen to be provided to the client device. That is, the client device receives and plays back the game screen generated by the rendering processing executed by the server, thus displaying the game screen. However, a practical method of sharing the rendering processing by a plurality of devices has not been disclosed yet.